The appearance of the appropriate oligomeric forms of acetylcholinesterase (AChE) at the neuromuscular synapse is known to be regulated by neuronal factors and muscle activity. In this application we propose to study the role of second messengers such as 3',5'-cyclic adenosine monophosphate (cAMP), inositol phospholipids, and 1,2- diacylglycerol (DAG) on the transcriptional and translational control of skeletal muscle AChE. The signal transduction systems will be characterized by quantification of cAMP, phosphoinositol and diacylglycerol production and protein kinase C activity determination in response to nicotinic and muscarinic receptor agonists. The synthesis and assembly of AChE from skeletal muscle cell culture will be determined as a function of cholinergic agonist induced depolarization and of direct manipulation of second messengers. This study also includes the analysis of AChE mRNA expression and translation and its correlation with the activation of cholinergic receptors and second messenger systems. The results obtained from these studies will be important to understand the intracellular mechanisms responsible for the regulation of synaptic proteins at cholinergic synapses and the role of different receptors and second messenger systems.